This invention relates to disk drives and, more particularly, to time-slicing techniques employed in disk drives having a programmed data processor control system.
Real time control systems require the pseudo-simultaneous servicing of a number of system functions. By "pseudo-simultaneous" it is meant that in the macro-time scale (e.g. ms and up), the system functions appear to be occurring simultaneously. In fact, in the micro-time scale, since most programmed data processors can only execute one instruction at a time, only one function can be serviced at a time. The pseudo-simultaneous effect has, in the past, been accomplished by a technique known as "time-slicing." In accordance with known time-slicing methods, each function will be serviced, but not necessarily to completion, for a very short period of time (e.g. in the microsecond range). A second function will then be serviced for an equally short period of time, and so on until all necessary functions have received attention, at which time the first function will again be serviced, and so on.
It would be desirable to provide an improved time-slicing apparatus especially suited for a disk drive of the type having a programmed data processor control system.